The art of the present invention relates to surgical instruments and cannulas for surgical use and more particularly to a flexible cannula which substantially seals with or within an incision and allows a surgical instrument of a width or dimension greater than the inside round undeformed diameter of the cannula to fit through the cannula via elastic deformation of said cannula while continually sealing the incision through which said cannula is placed. The present art utilizes a combination of a uniquely modified microvitreoretinal blade or obturator assembled in conjunction with the flexible cannula whereby a self sealing and substantially flat incision is created for placement and use of said cannula. The substantially flat incision in combination with the flexible cannula allows a surgeon to create a larger incision which accommodates a larger instrument (such as a 20 gauge surgical instrument) through said cannula, all while maintaining the desirability of a self sealing incision. The art of the present invention is especially useful during ophthalmic or eye surgeries.
Prior art devices and methods utilize generally inflexible or rigid cannulas to introduce instrumentation within or into an organ during surgery, including but not limited to surgeries within the globe of the eye. Typically, the prior art is manufactured from a substantially rigid polyimide or stainless steel material or tubing which does not easily accommodate the deformation necessary for insertion of an instrument that violates the envelope (i.e. inside diameter) of the cannula tube or tubing. A conventional cannula typically consists of a head and a cannula tube or tubing and often has a trocar or sharp instrument portion on said tube in order to puncture or insert into a body organ. The head serves to position or stop the cannula at the correct insertion depth. Said head also serves to guide the surgical instrument into said cannula tube and further provides for convenient removal of the cannula following a surgical procedure. That is, the head is easily grasped for removal. During surgeries of the eye, the cannula tube is the passageway through the eye wall that allows a surgical instrument access to the interior regions of the eye globe. Prior art methods of attaching or mounting the cannula tube with the cannula head also limited cannula deformation and thereby limited the ability the cannula to accommodate an instrument which violates the cannula envelope.
Prior art cannula methods of use often create an incision with a hypodermic needle or beveled wire utilized as an obturator prior to cannula insertion. The needle creates a circular hole or semi-circular incision within the body organ into which the substantially non-flexible cannula is inserted. Said circular hole or semi-circular incision is required for insertion and accommodation of non-flexible cannulas. Unfortunately, said circular or semi-circular incision is generally not self sealing when the cannula is removed, except for approximately 25 gauge incisions. This is especially true for larger cannula sizes such as 20 gauge. If the incision, hole, or wound is not self sealing, sutures are required to close the wound, which procedure is generally more invasive and traumatic to the patient.
Cannula systems minimize trauma to the surrounding tissue during surgery as the incision remains open and protected. This advantage is especially useful during retinal surgeries as instruments are continuously introduced, manipulated, and removed through an incision within the eye globe or through the sclera. Often cannulas, including the head and tube portions, are sized for insertion of 20, 23, and/or 25 gauge instruments with other sizes available.
Conventional cannula limitations require that instruments introduced there through are smaller than or do not violate the envelope defined by the inner diameter walls of the cannula tube or head. The present art utilizes an extremely thin wall tubing that purposely deforms around the introduced surgical instrumentation and allows deformation of the incision without harm to said incision. The present art also utilizes a uniquely designed microvitreoretinal (MVR) type blade or obturator in combination with the deformable cannula. That is, the present art comprises a head and cannula tube with said cannula tube or tubing attached with or to said head whereby the cannula tubing retains the ability to elastically deform, all of which is assembled onto a shaft of a unique MVR blade or obturator which provides a substantially flat incision and easy insertion of the cannula. Said elastic deformation allows introduction of instruments through said cannula tube which are unable to fit through prior art devices. This is especially true for flattened instruments such as MVR blades whereby the flexible cannula tube allows a smaller incision to accommodate a wider instrument which heretofore required a larger more traumatic incision.
The deformable cannula tube and method of use of the present art is also less traumatic on the eye wall and scleral tissue during ophthalmic surgeries since the present art substantially closes or seals when an instrument is not inserted there through and into the eye. That is, the present art method of use utilizes a “slit” or substantially flat incision (typically formed with the described obturator) instead of a circular hole typically created by a hypodermic needle or trocar. The sealing or closing substantially reduces or eliminates the requirement for incision plugs as leaking from the organ, especially the eye, is substantially eliminated when the deformable cannula of the present art pinches closed. The present art apparatus further allows cannula insertion with or via the incision created by a substantially flat yet modified MVR blade or obturator. That is, when fed through the flexible cannula tube prior to surgical placement, the uniquely combined MVR blade or obturator may create the incision, insert the cannula placed upon the shaft of said obturator, and thereafter be removed from or back through the flexible tube whereby further instruments may be introduced through said cannula. The present art apparatus and method of use eliminates the multi-step requirement of creating an incision tangential to the sclera with an MVR blade or hypodermic needle, removing the blade, then inserting an appropriately sized trocar into the incision to accommodate the cannula tube size. With the current prevalence of 23 gauge (and larger with the present art valved embodiment) non-suture surgery, single step cannula insertion is less traumatic and substantially quicker and more convenient.
The art of the present invention may be used in and with many types of surgical procedures, especially including but not limited to ophthalmic procedures.
Accordingly, it is an object of an embodiment the present invention to provide a flexible walled cannula having a deformable cannula tube which accommodates an instrument of a greater width than the tube inside diameter without injury to the surgical site or patient.
Another object of an embodiment of the present invention is to provide a flexible walled cannula which when used with the present art obturator substantially closes or seals at the insertion site when an instrument is not inserted through the apparatus.
A further object of an embodiment of the present invention is to provide a flexible walled cannula apparatus and method of use which allows a surgeon to insert the cannula in conjunction with a specially formed obturator and provide a substantially automatic seal at the insertion site without the use of specialty cannula plugs when the obturator is removed.
A still further object of an embodiment of the present invention is to provide a flexible walled cannula combined with an obturator as an apparatus and method of use which promotes post surgical healing via utilization of a slit or substantially flat incision instead of a prior art circular hole and is minimally invasive to the patient.
A yet further object of an embodiment of the present invention is to provide a flexible walled cannula combined with an obturator as an apparatus and method of use which allows a surgeon to utilize larger diameter (i.e. lower gauge) instruments than previously have been commonly used, while maintaining a desirable self sealing incision.